This invention relates generally to fission counters and more particularly to fission counters for monitoring the neutron flux in a nuclear reactor core.
In nuclear reactor operation it is required to know the specific power at several locations throughout the reactor core. These measurements ensure that the local power does not exceed specified allowed values which could result in local fuel damage.
The primary way of determining local power is by inference from neutron flux data obtained from fission chambers operating in the DC current mode or from self-powered neutron detectors. These detectors are placed in a dozen or more instrument tubes that are located throughout the reactor core. Because each ionization chamber requires its own signal cable, only about 4 chambers can be fitted into an instrument tube. With a typical core length of approximately 3.6 meters, a detector spacing of almost one meter at each tube location is thus dictated. A smaller spacing is desirable for improved resolution of local power measurements in both power producing and experimental nuclear reactors.